1. Field of Invention
The present invention relates to lighting means having sockets operable to receive and power 120 Volt incandescent light bulbs but wherein the socket voltage is conditioned such as to make it substantially free from electric shock hazard.
2. Background and Prior Art
According to Article 725 of NATIONAL ELECTRICAL CODE 1984--issued by NATIONAL FIRE PROTECTION ASSOCIATION, BATTERYMARCH PARK, QUINCY, MASS. 02269--as long as output current may exceed 0.005 Amp, a Class-2 electrical circuit is limited to a maximum output voltage of 30 Volt RMS for sinusoidal voltages at power line frequencies. Based on experience, this voltage level is considered to be acceptably safe from electric shock hazards.
A wide variety of plug-mounted Class-2 power supplies are available for purchase. A typical example of such a power supply is a plug-in battery eliminator for a hand-held calculator.
At frequencies substantially higher than 60 Hz, the human body exhibits a significant degree of so-called skin-effect; which causes less penetration of current into the human body while at the same time making the human body more resistive to the flow of current.
For instance, at a frequency of 60 Hz, it is relatively harmless for a person to receive an electric shock that results in a current as high as 0.005 Amp. At 30 kHz, on the other hand, it is about equally harmless for a person to receive an electric shock that results in a current as high as 0.03 Amp.